A starship has been sent to the planet Marego to defeat the invading rebels who bring with them a precious power crystal. This crystal (so powerful it has to be stored under oil!) is gradually polluting the life-supporting atmosphere. Unfortunately, the exploration team were attacked by rebels - two escaped, though. These two agents (controlled from the mothership via inbuilt communicators) must recover the crystal and bring back some seaside, ummm, geological rock and water samples.

The top of the screen is split in two - half for each independent agent. Each is controlled using simple verb/noun commands (the instructions state that the agents were brainwashed and can now only understand simple orders - how convenient!). Control is automatically switched to the other agent after one has moved, but this can be effectively switched off by telling one agent to WAIT.

The concept of having two agents is not simply a gimmick, each has different attributes. Agent One is strong but can't understand a word of the local lingo, so he's unable to read signs etc. On the other hand, Agent Two is more of an intellectual, but hardly Arnold Schwarzenegger!

Firstly, you must get both agents together to help each other. This is made difficult by an obstructing blank door as well as each agent having problems that the other could easily solve (if only he were there). For example, Agent One can find a computer but is unable to operate 'the confounded contraption', let alone read the words on the screen. A great deal of lateral thinking is needed to solve some of the perplexing puzzles. To aid progress in this difficult environment, a useful RAMSAVE option is included, as well as the standard tape SAVE.

All this exercising of the old grey matter might get a hit much if it wasn't for the little snippets of humour. The agents reply with such classics as 'You're having me on' and 'You're winding me up', and help to give themselves some personality.

The display is well laid out and clear. Location descriptions are kept short but contain everything you need to know, while all objects can be examined. Double Agent is an innovative piece of home-grown software featuring some intriguing interaction between the two agents. An extra bonus is the very witty (terribly corny) Escape on the flip side. This simply involves escaping from a prison cell with the help of a friendly wizard and a genie. It's quickly solved, as plenty of hints are given in the text. But it's funny, and a nice freebie to complement the difficult, main text-only adventure.

And if this isn't enough value for money, Tartan Software are also offering a £50 prize for the sender of the shortest solution to Double Agent. Get cracking, the closing date is November 30...

Double Agent is available from Tartan Software, 61 Bailie Norrie Crescent, MONTROSE, Angus, Scotland DD10 9DT.